The Occurrence State and Restraint Factors of Helium-produced Elements (U, Th) in the Granites from the Southern Margin of Weihe Basin: Evidences from Huashan Complex

Granites have been constantly concerned and much progress has been achieved on the production, storage and release of helium. However, there is lack of further study about the occurrence state, restraint factors and effective assessment of helium-produced elements (U, Th) in the granites when granites had been generated. A large number of granitic batholiths, located at the southern margin of Weihe basin, were considered to be the crucial source of helium. This study focused on the representative Huashan granitic batholith. The EMPA analyses and identifications for placer minerals showed that U and Th were mainly stored in zircons, titanites and apatites from Huashan granitic batholith. The Th content was mostly depended on the content of zircon and U content was controlled by zircon and allanite in the Yanshanian pluton, while Th and U content were dominantly related to zircon, titanite and minor thorite in the Indonian pluton. Meanwhile, the contents of U and Th in the samples mentioned above were determined and synthetical study suggested that the Taihua complex with various gneisses and the degree of parting melting were the dominant two factors for the divergence of U and Th in the Huashan granite.